Building on the existing crosslinguistic research on wh-questions with coordinated wh-pronouns, in this paper we turn to relative clauses and examine the effects of coordination on the grammaticality of relative clauses with multiple relative pronouns. We first discuss a general restriction on relativization, which bans multiple relativization from a single clause. We attribute this restriction to either a syntactic violation (impossible promotion of the head) or a semantic violation (semantic mismatch between the head and the relative clause). Next, we turn to free and headed relatives with coordinated wh-pronouns, showing that they do not display the same amount of crosslinguistic variation as wh-questions with coordinated wh-pronouns. In particular, irrespective of the availability of a mono-clausal structure for wh-questions with coordinated wh-pronouns in a language (which in turn correlates with the availability of multiple wh-fronting), a mono-clausal structure for free relatives with coordinated wh-pronouns is not available. In this respect, free relatives pattern with headed relatives rather than wh-questions. We derive this parallelism from a fundamental difference between relative clauses and questions: the presence of a CP external head in relative clauses, but not in wh-questions.